Respuesta :
INFORMATION:
We know that:
- John sells plain cakes for $8 and decorated cakes for $12.
- On a particular day, John started with a total of 100 cakes, and sold all but 4.
- His sales that day totaled $800.
And we must find the number of plain cakes and decorated cakes that he sold that day.
STEP BY STEP EXPLANATION:
To find them, we can represent the situation using a system of equations
[tex]\begin{cases}x+y={100-4...(1)} \\ 8x+12y={800...(2)}\end{cases}[/tex]Where, x represents the number of plain cakes that he sold and y represents the number of decorated cakes that he sold.
Now, we must solve the system:
1. We must multiply the equation (1) by -8
[tex]\begin{gathered} -8(x+y)=-8(100-4) \\ -8x-8y=-768...(3) \end{gathered}[/tex]2. We must add equations (2) and (3)
[tex]\begin{gathered} 8x+12y=800 \\ -8x-8y=-768 \\ ---------- \\ 0x+4y=32 \\ \text{ Simplifying, } \\ 4y=32...(4) \end{gathered}[/tex]3. We must solve equation (4) for y
[tex]\begin{gathered} 4y=32 \\ y=\frac{32}{4} \\ y=8 \end{gathered}[/tex]4. We must replace the value of y in equation (1) and then solve it for x
[tex]\begin{gathered} x+8=100-4 \\ x=100-4-8 \\ x=88 \end{gathered}[/tex]So, we found that x = 88 and y = 8.
Finally, John sold 88 plain cakes and 8 decorated cakes.
ANSWER:
He sold 88 plain cakes and 8 decorated cakes that day.
